Eddie Alvarez, one of the most accomplished lightweight martial artists of all time, has signed an exclusive deal with Asia-based fight promotion One Championship.

One Championship officially announced the signing on Monday evening. Founder Chatri Sityodtong also posted a video of Alvarez confirming the news to social media.

"Hey guys, moment of truth has arrived," Alvarez said. "I know you heard the rumors, and they are true ... This couldn't have went any smoother. It didn't take too long. Everybody is happy. I'm super excited 'The Underground King' is coming to One FC."

One Championship did not reveal a date or opponent for Alvarez's debut.

Alvarez (29-6), of Philadelphia, has held lightweight titles in the UFC and Bellator MMA, and holds a win over longtime Strikeforce champion Gilbert Melendez.

The 34-year-old elected to fight out his exclusive UFC contract in July, in a five-round main event against Dustin Poirier. Alvarez was in a dominant position in the second round, but lost it due to an illegal elbow. He suffered a TKO loss moments after getting stood up.

He won the UFC's 155-pound title in July 2016, but surrendered it in his first attempted defense against Conor McGregor at UFC 205. Alvarez engaged in contract extension talks with the UFC earlier this year, but the two sides were unable to come to an agreement.

One Championship was founded in 2011 and focuses exclusively on Asian markets. The promotion's 155-pound title is currently vacant.